1. Field of the Invention
The invention relates to network management in general, and in particular, to discovering the location of Management Stations and managed devices in the network.
2. Prior Art
The proliferation of computer networks has created a demand for improved apparatus and method for managing such networks. The management need is even greater because the networks are growing larger and more complex. Most conventional computer networks are comprised of stations (for example, word processors, personal computers, etc.) interconnected by communications infrastructure. Included in the communications infrastructure are routers, bridges, transmission media, gateways, switches, etc. The computer networks could be simple ones in which the stations are configured in a room, or a more elaborate ones in which the stations are distributed over a large geographical area, such as a large building, company site, a campus or several towns.
In more complex networks, one or more of the stations are designated Management Stations. One of the functions provided by Management Stations is keeping track of devices (called managed devices) as they (the managed devices) enter and/or leave the network. To provide tracking and other management functions, a Management Program, such as the Simple Network Management Protocol SNMP is executed in the Management Station and in the managed device. The portion of SNMP which is executed in the managed device is termed SNMP agent. Usually, the activities of managed devices are maintained in a data base (file) at the Management Station and can be used by the Management Station itself or a network operator to detect and/or correct fault in the network.
The conventional approach, to network management, addresses SNMP Management Stations and the SNMP managed devices operating at the LLC level of the protocol stack. The conventional technique uses an appropriate protocol, such as the well-known Internet Protocol (IP), to communicate and to "auto-discover" the SNMP managed devices or devices. Even though the approach works well for discovering LLC level devices, there are other network devices, termed MAC layer devices, which do not respond very well to LLC level protocols. The MAC (Medium Access Control) layer devices may include routers, concentrators, hubs, switches or like devices. As a consequence, these MAC layer devices are usually not discovered, by the Management Stations, using the conventional approach.
Several prior art patents describe devices and method for managing computer networks. The following patents are examples of the prior art devices and methods.
U.S. Pat. No. 5,233,510 describes a method of continuously self-configuring of a computer control system used in a manufacturing process. Each object in the process is assigned a unique ID or address. Each object in the manufacturing process uses its unique ID in all communications with other objects in the process. With this information, a control computer can locate and map all of the objects that are in the process.
Japanese patent number JP-3-123137 deals with the manual configuration of a MAC address into the forwarding table of a MAC layer bridge and storing these addresses into an NVRAM. Most MAC layer bridges "listen" to the MAC addresses on either side of the bridge and dynamically build forwarding tables. This patent provides a way to manually build this table eliminating the need for the bridge to "learn" the addresses.
U.S. Pat. No. 5,282,270 deals with the discovery of network devices that exists in a network running the AppleTalk protocol. The patent defines how routers within the AppleTalk protocol determine the location of the network element. The patent uses a multicast address which all routers running the AppleTalk recognize. The information passed between routers in these multicast frames is used to locate network elements.
U.S. Pat. No. 4,991,089 deals exclusively with workstations attached to a SNA network using the LU6.2 specification. The patent defines the method where the workstation notifies a host system of its terminal address via the SNA protocol.
U.S. Pat. No. 4,914,571 describes a method for locating resources in a computer network so that a session can be established between an origin and a destination station. The patent relates specifically with the SNA protocol. The LOCATE METHOD defined in the patent uses the SNA protocol to search for the destination target.
U.S. Pat. No. 5,408,618 discloses an Automatic Configuration Mechanism (ACM) which can be used by a node in a LAN to obtain configuration information from other nodes, to provide configuration information to other nodes and to respond to other nodes which seek configuration information. The frame format of this patent operates at the LLC layer of the ISO protocol stack.
U.S. Pat. No. 5,185,860 describes a method by which a Network Management Station (NMS) can "auto" discover devices containing SNMP agents in a network using TCP/IP protocol. Of all the above cited prior art, this patent appears most relevant to the field in which applicants' invention operates. However, it covers the discovery process as it relates to the Management Station only and does not address discovery as it applies to an agent.
As networks become more complex and dynamic, addition and relocation of devices are likely to occur more frequently. As a consequence, new procedures and devices are required to "auto" discover changes in the network.